AAR activation caused the expected increase in transcription factors that mediate specific AAR pathways, as well as the induction of asparagine synthetase, a terminal AAR target gene.
Using several human CRC cell lines and clinical specimens of primary CRC, we demonstrated that the expression of asparagine synthetase (ASNS), an enzyme that synthesizes asparagine from aspartate, was upregulated by mutated KRAS and that ASNS expression was induced by KRAS-activated signaling pathway, in particular PI3K-AKT-mTOR pathway.

Transcription from the ASNS (asparagine synthetase) gene is increased in response to either amino acid (amino acid response) or glucose (endoplasmic reticulum stress response) deprivation. These two independent pathways converge on the same set of genomic cis-elements within the ASNS promoter, referred to as nutrient-sensing response element-1 and -2.

L-Asparaginase (l-ASP), a bacterial enzyme used since the 1970s to treat acute lymphoblastic leukemia, selectively starves cells that cannot synthesize sufficient asparagine for their own needs. Molecular profiling of the NCI-60 cancer cell lines using five different microarray platforms showed strong negative correlations of asparagine synthetase (ASNS) expression and DNA copy number with sensitivity to l-ASP in the leukemia and ovarian cancer cell subsets. To assess whether the ovarian relationship is causal, we used RNA interference to silence ASNS in three ovarian lines and observed 4- to 5-fold potentiation of sensitivity to l-ASP with two of the lines. For OVCAR-8, the line that expresses the least ASNS, the potentiation was >500-fold. Significantly, that potentiation was >700-fold in the multidrug-resistant derivative OVCAR-8/ADR, showing that the causal relationship between ASNS expression and l-ASP activity survives development of classical multidrug resistance. Tissue microarrays confirmed low ASNS expression in a subset of clinical ovarian cancers as well as other tumor types. Overall, this pharmacogenomic/pharmacoproteomic study suggests the use of l-ASP for treatment of a subset of ovarian cancers (and perhaps other tumor types), with ASNS as a biomarker for patient selection.

FUNCTION: Has both L-asparaginase and beta-aspartyl peptidase activity. May be involved in the production of L-aspartate, which can act as an excitatory neurotransmitter in some brain regions. Is highly active with L-Asp beta-methyl ester. Besides, has catalytic activity toward beta-aspartyl dipeptides and their methyl esters, including beta-L-Asp-L-Phe, beta-L-Asp-L-Phe methyl ester (aspartame), beta-L-Asp-L-Ala, beta-L-Asp-L-Leu and beta-L- Asp-L-Lys. Does not have aspartylglucosaminidase activity and is inactive toward GlcNAc-L-Asn. Likewise, has no activity toward glutamine.CATALYTIC ACTIVITY: L-asparagine + H(2)O = L-aspartate + NH.CATALYTIC ACTIVITY: Cleavage of a beta-linked Asp residue from the N-terminus of a polypeptide.ENZYME REGULATION: Glycine accelerates autocleavage into an alpha and beta chain.BIOPHYSICOCHEMICAL PROPERTIES: Kinetic parameters: KM=3.4 mM for L-asparagine (L-Asn); KM=0.4 mM for L-aspartic acid beta-methyl ester; KM=0.4 mM for L-Asp-L-Phe; KM=1.0 mM for L-Asp-L-Ala;SUBUNIT: Heterodimer of an alpha and beta chain produced by autocleavage. This heterodimer may then dimerize in turn, giving rise to a heterotetramer.SUBCELLULAR LOCATION: Cytoplasm. Note=Midpiece of sperm tail.ALTERNATIVE PRODUCTS: Event=Alternative splicing; Named isoforms=2; Name=1; IsoId=Q7L266-1; Sequence=Displayed; Name=2; IsoId=Q7L266-2; Sequence=VSP_028287; Note=No experimental confirmation available;TISSUE SPECIFICITY: Expressed in brain, kidney, testis and tissues of the gastrointestinal tract. Present in sperm (at protein level). Over-expressed in uterine, mammary, prostatic and ovarian carcinoma.INDUCTION: By 5-alpha-di-hydrotestosterone and progesterone.PTM: Cleaved into an alpha and beta chain by autocatalysis; this activates the enzyme. The N-terminal residue of the beta subunit is responsible for the nucleophile hydrolase activity.SIMILARITY: Belongs to the Ntn-hydrolase family.SEQUENCE CAUTION: Sequence=BAB15302.1; Type=Erroneous initiation; Note=Translation N-terminally extended; Sequence=BAB15302.1; Type=Miscellaneous discrepancy; Note=Contaminating sequenc